Embodiments of the present invention relate to networking and more particularly to techniques for ring protection switching.
In a network, nodes interconnected by links can learn paths from various sources to various destinations over time. As these nodes learn such paths, the nodes can update internally stored tables in order to specify, for a data packet having a particular destination, the port of the node on which that data packet should be forwarded. When a link fails after such paths have been learned, at least some paths may need to be re-learned in order to compensate for the fact that paths containing the failed link are no longer viable; alternative paths will need to be learned in those cases.
The re-learning of paths following link failure can take a substantial amount of time, which is detrimental to the data-path switching performance within the network. Fortunately, the configuration of nodes using a protocol called Ethernet Ring Protection (ERP) protocol can somewhat simplify and quicken the re-learning process by confining relearning only over ring nodes of one ring. The Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T) G.8032 Ethernet Ring Protection Switching (ERPS) standard defines the automatic protection switching (APS) protocol and protection switching mechanisms for Ethernet layer network (ETH) ring topologies, including details pertaining to ERP characteristics, architectures, and the ring APS (R-APS) protocol. An important aspect of deploying the G.8032 ERPS protocol to customers is its performance in detecting failure on a ring, such as a signal failure on one of the ports or a node failure, and restoring the traffic. Media access control (MAC) address flush is one of the most important factors that determine the time taken to restore the traffic.